1. Field of the Invention
The present invention relates mainly to a movable optical head in a separated optical head system, that is, an objective lens drive apparatus in an optical information recording apparatus of magneto-optical type or of optical type.
2. Related Background Art
A conventional objective lens drive apparatus of such a type is structured such that, in optically conducting information recording by radiating a light spot onto a recording medium in the form of a disk, an actuator for an objective lens is held along a guide rail to conduct a tracking control of the objective lens for a light spot in a radial direction of the recording medium and that the actuator is controlled to move the objective lens with a proper driving force in the seeking direction or in the tracking direction.
In order to urge a weight reduction in a movable portion or the optical head For high speed processing of the information recording apparatus, many efforts have been made to reduce and simplify optical elements on the actuator side of the objective lens and the movable portion of the tracking and focusing control system as much as possible. A new structure for further weight reduction is proposed to omit the mounting of elements for a fine tracking function on the movable portion while using a galvano mirror, as presented in presentations at academic conferences.
Even in the information recording apparatus employing the above-mentioned galvano mirror, the objective lens drive apparatus, however, requires an actuator for driving the objective lens in the focusing direction and a carriage for moving the actuator in the seeking direction. Therefore, satisfactory weight reduction has not been attained even in such an apparatus yet.